Semiconductor photonic devices, such as lasers, have an active structure in which electrons and holes are converted into photons to produce optical emissions. FIG. 1 illustrates a cross-sectional view of prior art semiconductor laser 100. When a positive electrode is connected to p-type electrical contact 110 and negative electrodes are connected to n-type electrical contacts 120 and 125, and a voltage is applied, laser 100 becomes forward biased. Electrical current (i.e., holes and electrons) is injected towards active layer 130. Holes in p-type region 102 move in a direction away from p-type electrical contact 110 toward n-type electrical contacts 120 and 125; electrons in relatively thin n-type layer 160 move in a direction away from n-type contacts 120 and 125 toward p-type electrical contact 110. It will be understood that the active structure of laser 100 includes optical mode 135 and active region 190, which is a portion of active layer 130 included in optical mode 135. As the holes and electrons meet at active region 190, the holes and electrons combine to emit light.
Prior art laser 100 also includes current confinement structures 153-154 that serve to channel the injected current towards active region 190, and optical confinement structures 151-152 to form optical mode 135. These confinement structures increase light conversion efficiency by reducing the amount of current injected into areas of active layer 130 where the resulting light produced is not guided within optical mode 135. Optical mode confinement structures in prior art laser 100 are thus necessary in substrate region 101 (structures 151 and 152, along with layer 170) and current confinement structures are necessary within the p-type region 102 (structures 153 and 154).
Optical confinement structures 151 and 152 may be selectively oxidized or etched portions of substrate region 101. These confinement structures do not conduct current, and thus cause the current to be channeled towards active region 190 along relatively thin n-type layer 160. The width of optical confinement structures 151 and 152 is dictated by the desire to reduce the loss of light transmitted outside optical mode 135 due to leakage of light through the confinement structure.
P-type region confinement structure 153 and 154 may be regions bombarded or implanted with protons. This implantation makes structures 153 and 154 semi-insulating, which ensures that holes will not pass through these areas, but will be channeled between them and towards active region 190. Structures 153 and 154 must be a certain distance from active region 190 to eliminate the possibility of implant damage that will cause some of the injected current to spread and leak outside of the confined area. This distance required between said confinement structures and active region 190 reduces current injection efficiency as regions of active layer 130 that do not overlap optical mode 135 produce light not emitted into the optical mode.
The above confinement structure creation techniques further result in the device having poor thermal performance due to material loss where the material was etched away to form structures 151 and 152. The areas that heat may dissipate away from active region 190 are restricted due to structures 151 and 152 and layer 170. Prior art solutions to improve thermal performance have included creating thermal shunts in a lasing device, but this solution requires additional processing steps.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.